Re: [PATCH v3 23/30] mm: do not open-code lruvec lock

[Qi Zheng <qi.zheng@linux.dev>]

On 1/15/26 5:26 PM, Baoquan He wrote:
> On 01/14/26 at 07:32pm, Qi Zheng wrote:
>> From: Qi Zheng <zhengqi.arch@bytedance.com>
>>
>> Now we have lruvec_unlock(), lruvec_unlock_irq() and
>> lruvec_unlock_irqrestore(), but not the paired lruvec_lock(),
>                                    ~~ typo, 'no'?
>> lruvec_lock_irq() and lruvec_lock_irqsave().
>>
>> There is currently no use case for lruvec_lock_irqsave(), so only
>> introduce lruvec_lock() and lruvec_lock_irq(), and change all open-code
> 
>    I didn't see lruvec_lock() is introduced in this patch, do I miss
>    anthing?

I forgot to update commit message when I deleted lruvec_lock(), will
modify it in the next version.

Thanks!

> 
>> places to use these helper function. This looks cleaner and prepares for
>> reparenting LRU pages, preventing user from missing RCU lock calls due to
>> open-code lruvec lock.
>>
>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
>> ---
>>   include/linux/memcontrol.h |  5 +++++
>>   mm/vmscan.c                | 38 +++++++++++++++++++-------------------
>>   2 files changed, 24 insertions(+), 19 deletions(-)
>>
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index f1556759d0d3f..4b6f20dc694ba 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -1499,6 +1499,11 @@ static inline struct lruvec *parent_lruvec(struct lruvec *lruvec)
>>   	return mem_cgroup_lruvec(memcg, lruvec_pgdat(lruvec));
>>   }
>>   
>> +static inline void lruvec_lock_irq(struct lruvec *lruvec)
>> +{
>> +	spin_lock_irq(&lruvec->lru_lock);
>> +}
>> +
>>   static inline void lruvec_unlock(struct lruvec *lruvec)
>>   {
>>   	spin_unlock(&lruvec->lru_lock);
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index f206d4dac9e77..c48ff6e05e004 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -2020,7 +2020,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
>>   
>>   	lru_add_drain();
>>   
>> -	spin_lock_irq(&lruvec->lru_lock);
>> +	lruvec_lock_irq(lruvec);
>>   
>>   	nr_taken = isolate_lru_folios(nr_to_scan, lruvec, &folio_list,
>>   				     &nr_scanned, sc, lru);
>> @@ -2032,7 +2032,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
>>   	count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned);
>>   	__count_vm_events(PGSCAN_ANON + file, nr_scanned);
>>   
>> -	spin_unlock_irq(&lruvec->lru_lock);
>> +	lruvec_unlock_irq(lruvec);
>>   
>>   	if (nr_taken == 0)
>>   		return 0;
>> @@ -2051,7 +2051,7 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
>>   	count_memcg_events(lruvec_memcg(lruvec), item, nr_reclaimed);
>>   	count_vm_events(PGSTEAL_ANON + file, nr_reclaimed);
>>   
>> -	spin_lock_irq(&lruvec->lru_lock);
>> +	lruvec_lock_irq(lruvec);
>>   	lru_note_cost_unlock_irq(lruvec, file, stat.nr_pageout,
>>   					nr_scanned - nr_reclaimed);
>>   
>> @@ -2130,7 +2130,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>>   
>>   	lru_add_drain();
>>   
>> -	spin_lock_irq(&lruvec->lru_lock);
>> +	lruvec_lock_irq(lruvec);
>>   
>>   	nr_taken = isolate_lru_folios(nr_to_scan, lruvec, &l_hold,
>>   				     &nr_scanned, sc, lru);
>> @@ -2141,7 +2141,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>>   		__count_vm_events(PGREFILL, nr_scanned);
>>   	count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned);
>>   
>> -	spin_unlock_irq(&lruvec->lru_lock);
>> +	lruvec_unlock_irq(lruvec);
>>   
>>   	while (!list_empty(&l_hold)) {
>>   		struct folio *folio;
>> @@ -2197,7 +2197,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>>   	count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate);
>>   	mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
>>   
>> -	spin_lock_irq(&lruvec->lru_lock);
>> +	lruvec_lock_irq(lruvec);
>>   	lru_note_cost_unlock_irq(lruvec, file, 0, nr_rotated);
>>   	trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate,
>>   			nr_deactivate, nr_rotated, sc->priority, file);
>> @@ -3832,9 +3832,9 @@ static void walk_mm(struct mm_struct *mm, struct lru_gen_mm_walk *walk)
>>   		}
>>   
>>   		if (walk->batched) {
>> -			spin_lock_irq(&lruvec->lru_lock);
>> +			lruvec_lock_irq(lruvec);
>>   			reset_batch_size(walk);
>> -			spin_unlock_irq(&lruvec->lru_lock);
>> +			lruvec_unlock_irq(lruvec);
>>   		}
>>   
>>   		cond_resched();
>> @@ -3993,7 +3993,7 @@ static bool inc_max_seq(struct lruvec *lruvec, unsigned long seq, int swappiness
>>   	if (seq < READ_ONCE(lrugen->max_seq))
>>   		return false;
>>   
>> -	spin_lock_irq(&lruvec->lru_lock);
>> +	lruvec_lock_irq(lruvec);
>>   
>>   	VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
>>   
>> @@ -4008,7 +4008,7 @@ static bool inc_max_seq(struct lruvec *lruvec, unsigned long seq, int swappiness
>>   		if (inc_min_seq(lruvec, type, swappiness))
>>   			continue;
>>   
>> -		spin_unlock_irq(&lruvec->lru_lock);
>> +		lruvec_unlock_irq(lruvec);
>>   		cond_resched();
>>   		goto restart;
>>   	}
>> @@ -4043,7 +4043,7 @@ static bool inc_max_seq(struct lruvec *lruvec, unsigned long seq, int swappiness
>>   	/* make sure preceding modifications appear */
>>   	smp_store_release(&lrugen->max_seq, lrugen->max_seq + 1);
>>   unlock:
>> -	spin_unlock_irq(&lruvec->lru_lock);
>> +	lruvec_unlock_irq(lruvec);
>>   
>>   	return success;
>>   }
>> @@ -4739,7 +4739,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
>>   	struct mem_cgroup *memcg = lruvec_memcg(lruvec);
>>   	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
>>   
>> -	spin_lock_irq(&lruvec->lru_lock);
>> +	lruvec_lock_irq(lruvec);
>>   
>>   	scanned = isolate_folios(nr_to_scan, lruvec, sc, swappiness, &type, &list);
>>   
>> @@ -4748,7 +4748,7 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
>>   	if (evictable_min_seq(lrugen->min_seq, swappiness) + MIN_NR_GENS > lrugen->max_seq)
>>   		scanned = 0;
>>   
>> -	spin_unlock_irq(&lruvec->lru_lock);
>> +	lruvec_unlock_irq(lruvec);
>>   
>>   	if (list_empty(&list))
>>   		return scanned;
>> @@ -4786,9 +4786,9 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
>>   	walk = current->reclaim_state->mm_walk;
>>   	if (walk && walk->batched) {
>>   		walk->lruvec = lruvec;
>> -		spin_lock_irq(&lruvec->lru_lock);
>> +		lruvec_lock_irq(lruvec);
>>   		reset_batch_size(walk);
>> -		spin_unlock_irq(&lruvec->lru_lock);
>> +		lruvec_unlock_irq(lruvec);
>>   	}
>>   
>>   	mod_lruvec_state(lruvec, PGDEMOTE_KSWAPD + reclaimer_offset(sc),
>> @@ -5226,7 +5226,7 @@ static void lru_gen_change_state(bool enabled)
>>   		for_each_node(nid) {
>>   			struct lruvec *lruvec = get_lruvec(memcg, nid);
>>   
>> -			spin_lock_irq(&lruvec->lru_lock);
>> +			lruvec_lock_irq(lruvec);
>>   
>>   			VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
>>   			VM_WARN_ON_ONCE(!state_is_valid(lruvec));
>> @@ -5234,12 +5234,12 @@ static void lru_gen_change_state(bool enabled)
>>   			lruvec->lrugen.enabled = enabled;
>>   
>>   			while (!(enabled ? fill_evictable(lruvec) : drain_evictable(lruvec))) {
>> -				spin_unlock_irq(&lruvec->lru_lock);
>> +				lruvec_unlock_irq(lruvec);
>>   				cond_resched();
>> -				spin_lock_irq(&lruvec->lru_lock);
>> +				lruvec_lock_irq(lruvec);
>>   			}
>>   
>> -			spin_unlock_irq(&lruvec->lru_lock);
>> +			lruvec_unlock_irq(lruvec);
>>   		}
>>   
>>   		cond_resched();
>> -- 
>> 2.20.1
>>
>>
>